<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Set</title>
</head>
<body>
<script type="text/javascript">
    let set = new Set();
    console.log(set)
    set.add("1");
    set.add(2);
    console.log(set.has(2));//true
    set.delete(2);
    set.forEach((key,value2)=>{
        console.log(key,value2)
    });
</script>
</body>
</html>